Telescopic umbrella

ABSTRACT

A telescopic umbrella includes a longitudinally extending crown on one end of the main shaft and both main and auxiliary sliders on the shaft. A rib assembly is pivotally secured to the flanks of the crown, main struts extend between the main slider and the rib assemblies and auxiliary struts extend between the main struts and the auxiliary slider. The plane formed by the rib assembly, main strut and auxiliary strut of at least one frame support unit is twistedly inclined with respect to a plane passing through the longitudinal axis of the shaft so that when the frame is folded these frame elements are not maintained in radial alignment so that the umbrella can be folded more compactly.

United States Patent Uthemann et al.

[ 1 Nov. 21, 1972 TELESCOPIC UMBRELLA Inventors: Wolfgang Uthemann; Richard Zimmermann, both of Leichlingen, Rhineland, Germany Assignees: W, Bauermann 8: Sohne Gmbh, Hilden, Germany; by said Uthemann; Rosenkaimer GmbH, Leichlingen, Rhineland, Germany; by said Zimmermann Filed: June 5, 1970 App1.No.: 43,704

Foreign Application Priority Data June 7, 1969 Germany ..G 69 22 739.0 June 10 1969 Germany ..P 19 29 471.4 Sept. 5, 1969 Germany ..P 19 45 098.7

US. Cl ..135/25 Int. Cl. ..A45b 19/08, A45b 19/10 Field of Search ..135/20 R, 25 R, 26 R, 28, 29

References Cited UNITED STATES PATENTS 1,213,855 1/1917 Flynn ..7135/28 Collins et al ..135/20 A 3,593,731 7/1971 Schultes ..135/25 R 1,049,360 1/1913 Hoffman ..135/26 R 3,431,925 3/1969 Kraft ..135/25 R Primary Examiner-Peter M. Caun Attorney-Markva and Smith [5 7] ABSTRACT A telescopic umbrella includes a longitudinally extending crown on one end of the main shaft and both main and auxiliary sliders on the shaft. A rib assembly is pivotally secured to the flanks of the crown, main struts extend between the main slider and the rib assemblies and auxiliary struts extend between the main struts and the auxiliary slider. The plane formed by the rib assembly, main strut and auxiliary strut of at least one frame support unit is twistedly inclined with respect to a plane passing through the longitudinal axis of the shaft so that when the frame is folded these frame elements are not maintained in radial alignment so that the umbrella can be folded more compactly.

19 Claims, 15 Drawing Figures PAIENTEDnuval m2 SHEET 2 OF 4 Wyn/Em INVEN TORS M/ mQZ/MMERMA/W BY f y, flaw M m ATTDIFNE Ys PATENTEDNUVZI m2 SHEET 3 IF 4 mfm rum-vs TELESCOPIC UMBRELLA This invention relates to a telescopic umbrella and more particularly to an umbrella which in the closed condition can be folded into a flat form.

In flat umbrellas the ribs are hinged to flat crowns and the struts to correspondingly flat sliders. By flat is meant that the crowns and the sliders have a longitudinally extending cross-sectional shape and the hinge points for the ribs and struts are disposed on the flanks of the longitudinally extending crowns and sliders. Thus, the various frame elements lie in a common plane running parallel with the longitudinal axis of the umbrella shaft so that when the umbrella is closed the struts and rib assemblies are maintained in alignment so that one frame member is piled upon another, and the umbrella cannot be folded as compactly as desired.

One disadvantage of previously known flat umbrellas having longitudinally extending crowns and sliders is that the tension on the umbrella fabric differs at various locations depending upon the distance of the ends of the ribs mounted on the crown from the axis of the main shaft. As a result, the umbrella has a non-circular configuration or the strain on the circular cover differs around its perimeter because of the different lengths of the rib assemblies supporting the fabric, since these differences in length cannot be fully compensated for by the elasticity of the fabric. The struts anchored to the narrow side of a longitudinal slider cause the ribs, the ends of which are farther from the shaft axis, to assume a higher position than those ribs having ends closer to the shaft axis. Distortions result in some of the identical sectors of the fabric cover, and the ribs extending from the broad sides of the crown will extend upwardly or sideways more than the ribs extending from the narrow sides. Although attempts have been made to overcome these difficulties by giving the ribs different lengths, this has proved unsatisfactory from a manufacturing standpoint.

An object of the present invention is to provide in a telescopic umbrella an arrangement of frame members which will maintain their symmetry and not distort the cover.

This and other objects are achieved by providing that at least one of the umbrella frame support units comprising a rib assembly with the struts shall be twistedly inclined to the plane containing the longitudinal axis of the shaft when the umbrella frame is opened. Thus, at least some of the support units comprising a rib assembly and both main and auxiliary struts will have their roots adjacent the main shaft rotationally offset from each other. Thus, substantial portions of the length of the ribs and struts are laterally offset from each other in the folded condition resulting in smaller dimensions. This also offers the incidental further advantage that the crossing of corresponding frame portions causes frictional hinderance in the region of the sliding sleeves connecting the struts to the extensible parts of the rib assemblies. This is especially true when the opening of the folded umbrella is first initiated and the opening is thereby facilitated.

When the roots of the rib assemblies are hinged at different distances from the center point of the longitudinal crown and are thereby at different distances from the longitudinal axis of the shaft, the main and auxiliary struts are preferably hinged at equal distances from the longitudinal axis of the shaft.

The particular arrangement of the struts and rib assemblies rotatably offset from each other insures that a precisely shaped radially symmetrical cover can be combined in a simple manner with rib assemblies of equal telescopic length without additional stresses, distortions, and possibly excessive stresses arising as compared with an umbrella having a crown and slider of conventional form. The combination of the present invention permits the use of identical telescopic rib members, the roots of which are mounted at different distances from the axis of the main shaft. Radial symmetrical umbrella covers may be used without imposing excessive wear thereon. This is accomplished by the rib assemblies being telescopically assembled whereby compensation may be made by varying the degree of extension of the rib members. Furthermore, the relative positions of the ribs and corresponding struts are so arranged that they are not in radial alignment when folded permitting the umbrella to be folded more compactly and maintain its flat folded configuration.

The invention will now be described in greater detail with reference to the accompanying drawings wherein:

FIG. 1 is a side view partially in section of the frame of the umbrella;

FIG. 2 is a plan view of the crown and the ends of the connecting rib members of the umbrella frame;

FIG. 3 is a plan view of the auxiliary slider and the ends of the connecting auxiliary struts;

FIG. 4 is a plan view of the main slider and the ends of the connecting struts;

FIG. 5 is a partial plan view of the umbrella frame when open;

FIG. 6 is a longitudinal cross-sectional view of a modification of the auxiliary slider;

FIG. 7 is a plan view of the auxiliary slider of FIG. 6;

FIG. 8 is a longitudinal cross-sectional view of a modification of the main slider;

FIGS. 9 and 10 are plan views of different embodiments of the main slider of FIG. 8;

FIG. 11 is a schematic plan view of the umbrella frame;

FIGS. 12 and 13 are schematic side views of each of the two rib assemblies shown in FIG. 11;

FIG. 14 is a schematic plan view of a part of the umbrella including the cover in opened position; and

FIG. 15 is a partial side view of a further embodiment of the umbrella frame with one of its rib assemblies in folded position. I

The main shaft of the umbrella comprises shaft members 10 and 11 which are telescopically assembled, shaft member 10 being frictionally retained in a selected position with respect to shaft member 11. A flat handle 14 is secured to the free end of shaft member 10, and a crown 15 which is flat and has a shape similar to that of handle 14 is located at the free end of shaft member 11.

Each of the rib assemblies of the umbrella frame comprises inner and outer rib members 12 and 13 respectively which are telescopically assembled, outer rib member 13 being slidable into the interior of inner rib member 12. One end of each of the inner rib members 12 is pivotally secured to the crown 15. With reference to FIGS. 2 and 5, the two areas 16 and 17 of the crown 15 each carry four ribs which are at about a 45 angle with respect to each other. There is some variation in the angular relationship between the ribs since the pivot points of the rigs are unequally spaced from the longitudinal axis of the main shaft.

Each inner rib member 12 is of generally U-shaped cross-section between a point adjacent the pivot point at the crown 15 and a point adjacent the opposite end which terminates in a hollow sleeve 9. The open portion or slot of the U-shaped rib member 12 faces downwardly as seen in FIG. 1. The outer rib member 13 is cylindrical with a cross-section smaller than that of inner rib 12. One end of the outer rib member 13 passes through hollow sleeve 9 and is secured through the slot in the inner rib member 13 to sliding rib sleeve 18 which is generally cylindrical and is slidably mounted on the exterior of inner rib 12. The opposite end of outer rib member 13 includes a cap 36 with a hole for securing a loop on the edge of the umbrella cover 38.

Pivotally coupled to the sliding rib sleeve 18 is one end of a stretcher or strut 19, the opposite end of which is pivotally secured on the circular rim 20 of main slider 21 which itself is slidably mounted on shaft member 11. A plurality of struts 19 equal in number to the rib assemblies are spaced about the circular rim 20 of the main slider 21 equidistant from the axis of the main shaft but are divided into two groups with the angular relationship between the struts 19 within each group being 36 while the angular relationship between the adjacent end struts of the two groups is 72. The two groups of struts 19 are positioned transversely with respect to the two groups of inner rib members 12 as pivotally secured to the crown 15. Each of the struts 19 may be of generally U-shaped cross-section intermediate its ends, the open side facing upwardly as seen in FIG. 1.

An auxiliary slider 24 is slidably mounted on shaft 1 1 intermediate the main slider 21 and the crown 15. One end of each of a plurality of auxiliary struts 25 equal to the number of struts 19 are pivotally mounted equidistant from each other (45) on the circular rim 22 of the auxiliary slider 24. The opposite ends of the auxiliary struts 25 are pivotally mounted on struts 19 at a point intermediate their ends. A rubber ring 23 is mounted on the auxiliary slider 24 and serves as an opening aid. Rib members 12 and 13 with struts 19 and auxiliary strut 25 form a support unit and in the particular embodiment shown, eight such units are provided in the umbrella frame. The ribs and struts are pivotally secured to the crown, main slider and auxiliary slider by passing a wire through holes in the ends of the ribs and struts and securing the wire in a circumferential groove in the crown and sliders. The ends of the ribs and strutsfreely pivot in radial slots about the wire in the circumferential groove.

The umbrella cover 38 is anchored to the frame at the crown 15 with the edges having spaced loops which pass through the holes in the caps 36. Further loops are located between the center and edges of the cover and pass around each of the sliding rib sleeves 18.

The umbrella is retained under tension in open position by spring-biased latch 8 in the main slider 21 which engages a depression in shaft member 11. It will be noted in FIGS. and 11 that the inner rib members 12 are offset with respect to the inner ends of struts 19 and auxiliary struts 25. This offset relationship permits the umbrella frame to be folded more compactly since when the umbrella is folded the rib members 12 and struts 19 and 25 will not be in radial alignment permitting the rib members and struts to by-pass each other. It is preferable that the diameters of rims 20 and 22 of the main slider 21 and auxiliary slider 24 respectively do not exceed the width of the crown 15 and handle 14. When folded, most of the length of the shaft member is located inside shaft member 11 and latch 8 locks in recess 7 of shaft member 10. I

FIGS. 6 and 7 show a modified auxiliary slider 26 wherein the pairs of slots on opposite sides of the anchorage rim 27 are wedge-shaped while the other two pairs of slots 29 have parallel sidewalls. The wedgeshaped slots are disposed in line with the broad sides of the crown This provides increased freedom of movement to the auxiliary struts mounted in the wedge-shaped slots 28.

Two different embodiments of a modified auxiliary slider 30 are shown in FIGS. 8, 9 and 10. FIG. 9 shows the slots in the anchorage rim 31 equally spaced radially about the main slider. The pairs of slots 32 on opposite sides of the slider are wedge-shaped while the other two pairs of slots 33 have parallel walls. The wedge-shaped slots 32 are in line with the broad side of the crown 15. In FIG. 10 the slots 34 all have parallel sidewalls but are arranged in two groups, the groups being in line with the narrow sides of the crown. The arrangements in both FIGS. 9 and 10 permit movement of the struts 19 to compensate'for the unequal radial distances of the pivot points for the various rib members 12 from the axis of the main shaft of the umbrella. This is particularly important when the umbrella is folded to prevent distortion of the struts 19.

FIGS. 11, 12 and 13 compare diagrammatically the length relationships for two umbrella rib assemblies located at different distances from the axis of the main shaft. The total distance from the axis 35 to cap 36 is L, and the outer edge of all sliding rib sleeves 18 are a distance R, from the axis. Since the pivot point of rib member 12b is farther from axis 35 than the pivot point of rib member 12a, hollow sleeve 9b will extend beyond sliding rib sleeve 18b by a distance L This will be compensated for, however, by outer rib member 13b which is attached to sliding rib sleeve 18b and extends out of inner rib member 1212 by a distance less than outer rib member 130 extends out of inner rib member 12a.

In FIG. 15, a further embodiment of the umbrella frame is shown in folded position. The elements having the same numerical designation as those in FIG. 1 are identical to the corresponding elements of FIG. 1 and the description of these elements is applicable to this modification. Instead of a cap mounted on the free end of outer rib member 13, a hinge member is secured thereto. To this an outermost rib member 43 is pivoted. Thus, the rib assembly comprises three rib members instead of the two shown in FIG. 1. When the umbrella frame is opened the outermost rib member 43 will pivot radially outwardly in line with rib members 12 and 13 and will be prevented from pivoting downwardly by stop 42. A spacer plate 39 is located on the main slider 21 to prevent hinge member 40 entering the interior of the handle 14 which would cause jamming.

As the umbrella frame is folded, the main slider 21 moves downwardly along shaft members, 11 and 10.

This will cause sliding rib sleeve 18 to move along inner rib member 12 towards the crown drawing the outer rib member 13 into the inner rib member 12. Simultaneously, the auxiliary slider 24 will first move downwardly at a slower rate than the main slider 21, and as the folding step reaches completion, the auxiliary slider 24 will reverse direction and move upwardly along shaft member 11 to a position immediately below the crown 15. In the case of the modification shown in FIG. 15, it will be necessary to manually fold the outermost rib members 43 against the inner rib members 12 to complete the folding operation. The result is an extremely compact umbrella which is capable of being unfolded to conventional size.

We claim:

1. A folding umbrella comprising a. shaft means,

b. a plurality of rib assemblies each comprising an inner rib member and an outer rib member slidably mounted on said inner rib member whereby the length of each rib assembly may be varied, said inner and outer rib members being of substantially equal lengths respectively,

c. a crown substantially at one end of said shaft means, one end of each of said inner rib members being pivotally secured to said crown, the pivot points of said inner rib members being at varying distances from the axis of said shaft means,

d. a main slider movable along said shaft means, and

e. a plurality of main struts of equal length, one end of each main strut being pivotally secured to said main slider and the opposite end pivotally secured to said outer rib member, the pivot points where said main struts are secured to said main slider being substantially equidistant from the axis of said shaft means and in a common plane perpendicular to the axis of said shaft means, and the pivot points where said main struts are secured to said outer rib members being substantially equidistant from the free ends of said outer rib members,

f. whereby when the umbrella is fully opened the perimeter of the umbrella defined by the ends of the rib assemblies will be substantially circular with the overall distances between the axis of the shaft means and the free ends of the outer rib members being equal while the distances between the pivot points of said inner rib members and the free ends of said outer rib members vary.

2. A folding umbrella as defined in claim 1 further comprising an auxiliary slider movable along said shaft means between said main slider and said crown and a plurality of auxiliary struts of equal length, each auxiliary strut being pivotally mounted at one end to said auxiliary slider and at the opposite end to a main strut, the pivot points of said auxiliary struts at said auxiliary slider being equidistant from the axis of said shaft means and in a common plane perpendicular to the axis of said shaft means, and the pivot points of said auxiliary struts at said main struts being substantially equidistant from the pivot points where the main struts are secured to said outer rib members.

3. A folding umbrella as defined in claim 1 wherein said crown is longitudinally shaped with opposite ends and elongated sides, said pivot points of each of said inner rib members being located about the perimeter of said longitudinally shaped crown whereby the pivot points of said inner rib members are at varying distances from the axis of shaft means.

4. A folding umbrella as defined in claim 1 wherein said shaft means comprises a plurality of shaft members telescopically arranged whereby the length of said shaft means may be shortened or lengthened when said umbrella is folded or opened.

5. A folding umbrella as defined in claim 3 wherein said rib assemblies are arranged in two groups pivotally secured to the flanks of said longitudinally shaped crown, said groups being spaced from each other on opposite sides of a plane passing through the axis of said shaft.

6. A folding umbrella as defined in claim 5 wherein parallel walled slots are provided in the perimeter of said main slider for receiving and pivotally mounting the ends of the main struts, said slots being in two groups in axial alignment with the ends of said crown.

7. A folding umbrella as defined in claim 13 wherein the pivot points of said inner rib members are arranged forming a rectangular configuration on said crown about the axis of said shaft means.

8. A folding umbrella as defined in claim 2 wherein the main and auxiliary sliders comprise circular rims having slots for receiving the ends of the struts.

9. A folding umbrella as defined in claim 2 wherein the pivot points for the struts secured to at least one of the sliders are irregularly spaced from each other.

10. A folding umbrella as defined in claim 2 wherein slots are provided in the perimeters of said main and auxiliary sliders for receiving and pivotally mounting the ends of the struts, the slots in the sliders in axial alignment with the ends of the crown having parallel walls and the slots in axial alignment with the elongated sides of the crown having wedge-shaped slots.

11. A folding umbrella as defined in claim ll) wherein a pair of slots on opposite sides of the auxiliary slider are wedge-shaped and the remaining slots have parallel walls.

12. A folding umbrella as defined in claim Ml wherein a pair of slots on opposite sides of the main slider are wedge-shaped and the remaining slots have parallel side walls.

13. In a folding umbrella a. shaft means,

b. a plurality of rib assemblies each comprising an inner rib member and an outer rib member slidably mounted on said inner rib member whereby the length of each rib assembly may be varied, said inner and outer rib members being of substantially equal lengths respectively,

c. means for pivotally securing one end of each of said inner rib members about the axis of said shaft means,

. a main slider movable along said shaft means, and

e. a plurality of struts of equal length, one end of each strut being pivotally secured to said main slider and the opposite end pivotally secured to said outer rib member, the pivot points where said struts are secured to said main slider being in a common plane perpendicular to the axis of said shaft means and the pivot points where said struts are secured to said outer rib members being substantially equidistant from the free ends of said outer rib members, the pivot points of said inner rib members forming a different configuration about the axis of said shaft means than the configuration formed about the axis of said shaft means by said pivot points of said struts at said mean slider,

. whereby when the umbrella is fully opened the perimeter of the umbrella defined by the free ends of the rib assemblies will assume a configuration substantially the same as the configuration of the pivot points of said struts at said main slider.

14. A folding umbrella as defined in claim 13 wherein the pivot points of said rib assemblies are arranged forming a rectangular configuration about the axis of said shaft means and the pivot points of said struts are arranged forming a circular configuration about the axis of said shaft means.

15. A telescopic umbrella comprising a shaft,

b. a longitudinally extending crown located transversely on one end of said shaft, a main slider on said shaft,

d. an auxiliary slider on said shaft between said crown and main slider, and

. a plurality of frame support units each comprising a rib assembly, a main strut, and an auxiliary strut, each of said rib assemblies comprising an inner rib member and an outer rib member which are telescopically slidably assembled, said inner and outer rib members being of substantially equal lengths respectively,

. said rib assemblies being arranged in two groups pivotally secured to the flanks of said longitudinally extending crown, said groups being spaced from each other on opposite sides of a plane passing through the axis of said shaft, and the pivot points of said inner rib members on said flanks being at varying distances from the axis of said shaft,

. the main and auxiliary sliders comprising rims havthe opposite end of each of said main struts being pivotally secured to said outer rib members, the pivot points where said main struts are secured to said outer rib members being substantially equidistant from the free ends of said outer rib members,

. the opposite end of each of said auxiliary struts being pivotally secured to a main strut, the pivot points of said auxiliary struts at said main struts being substantially equidistant from the pivot points where the main struts are secured to said outer rib members,

k. whereby when the umbrella is fully opened the perimeter of the umbrella defined by the ends of the rib assemblies will be substantially circular.

16. An umbrella as claimed in claim 15 wherein the pivot points for the main and auxiliary struts are equally spaced around the periphery of the corresponding sliders.

17. An umbrella as claimed in claim 15 wherein parallel walled slots are provided in the perimeter of said main slider for receiving and pivotally mounting the ends of the main struts, said slots being in two groups in axial alignment with the narrow sides of said crown.

18. A telescopic umbrella frame comprising a. a shaft,

b. a longitudinally shaped crown substantially at one end of said shaft, said crown having a pair of flanks on opposite sides of said shaft, respectively,

. a main slider and an auxiliary slider both movable along said shaft, and

. a plurality of support units, each unit comprising a rib assembly, a main strut, and an auxiliary strut,

e. each said rib assembly comprising an inner rib member and an outer rib member slidably mounted on said inner rib member, whereby the length of each rib assembly may be varied, said inner rib members, outer rib members, main struts, and auxiliary struts being of substantially equal lengths respectively,

f. one end of each said main strut being pivotally secured to said main slider, said pivot points about said main slider being substantially equidistant from the axis of said shaft and being in a common plane perpendicular to the axis of said shaft, and the opposite end of each of said main struts being pivotally secured to said outer rib member, said pivot points where said main struts are secured to said outer rib members being substantially equidistant from the free ends of said outer rib members,

. one end of each said auxiliary strut being pivotally secured to said auxiliary slider, said pivot points about said auxiliary slider being substantially equidistant from the axis of said shaft and being in a further common plane perpendicular to the axis of said shaft, and the opposite end of each of said auxiliary struts being pivotally secured to said main strut, said pivot points of said auxiliary struts at said main struts being substantially equidistant from the pivot points where the main struts are secured to said outer rib members,

. one end of each of said inner ribs of said rib assemblies being pivotally secured to the flanks of said crown, the pivot points of said inner rib members being at varying distances from the axis of said shaft,

i. whereby the umbrella frame may be folded compactly and when opened the perimeter of the umbrella defined by the ends of the rib assemblies will be substantially circular.

19. In a folding umbrella a. shaft means,

b. a plurality of rib assemblies each comprising an inner rib member and an outer rib member slidably mounted on said inner rib member whereby the length of each rib assembly may be varied, said inner rib members and outer rib members being of substantially equal lengths respectively,

. means for pivotally securing one end of each of said inner rib members about the axis of said shaft means, the pivot points of said inner rib members being at varying distances from the axis of said shaft means,

d. a main slider movable along said shaft means, and

e. a plurality of struts of equal length, one end of each strut being pivotally secured to said main slider and the opposite end pivotally secured to said outer rib member, the pivot points where said struts are secured to said outer rib members being substantially equidistant from the free ends of said outer rib members, the pivot points where said struts are secured to said main slider being in a common plane perpendicular to the axis of said 10 shaft means, and the pivot points of said rib assem- 

1. A folding umbrella comprising a. shaft means, b. a plurality of rib assemblies each comprising an inner rib meMber and an outer rib member slidably mounted on said inner rib member whereby the length of each rib assembly may be varied, said inner and outer rib members being of substantially equal lengths respectively, c. a crown substantially at one end of said shaft means, one end of each of said inner rib members being pivotally secured to said crown, the pivot points of said inner rib members being at varying distances from the axis of said shaft means, d. a main slider movable along said shaft means, and e. a plurality of main struts of equal length, one end of each main strut being pivotally secured to said main slider and the opposite end pivotally secured to said outer rib member, the pivot points where said main struts are secured to said main slider being substantially equidistant from the axis of said shaft means and in a common plane perpendicular to the axis of said shaft means, and the pivot points where said main struts are secured to said outer rib members being substantially equidistant from the free ends of said outer rib members, f. whereby when the umbrella is fully opened the perimeter of the umbrella defined by the ends of the rib assemblies will be substantially circular with the overall distances between the axis of the shaft means and the free ends of the outer rib members being equal while the distances between the pivot points of said inner rib members and the free ends of said outer rib members vary.
 1. A folding umbrella comprising a. shaft means, b. a plurality of rib assemblies each comprising an inner rib meMber and an outer rib member slidably mounted on said inner rib member whereby the length of each rib assembly may be varied, said inner and outer rib members being of substantially equal lengths respectively, c. a crown substantially at one end of said shaft means, one end of each of said inner rib members being pivotally secured to said crown, the pivot points of said inner rib members being at varying distances from the axis of said shaft means, d. a main slider movable along said shaft means, and e. a plurality of main struts of equal length, one end of each main strut being pivotally secured to said main slider and the opposite end pivotally secured to said outer rib member, the pivot points where said main struts are secured to said main slider being substantially equidistant from the axis of said shaft means and in a common plane perpendicular to the axis of said shaft means, and the pivot points where said main struts are secured to said outer rib members being substantially equidistant from the free ends of said outer rib members, f. whereby when the umbrella is fully opened the perimeter of the umbrella defined by the ends of the rib assemblies will be substantially circular with the overall distances between the axis of the shaft means and the free ends of the outer rib members being equal while the distances between the pivot points of said inner rib members and the free ends of said outer rib members vary.
 2. A folding umbrella as defined in claim 1 further comprising an auxiliary slider movable along said shaft means between said main slider and said crown and a plurality of auxiliary struts of equal length, each auxiliary strut being pivotally mounted at one end to said auxiliary slider and at the opposite end to a main strut, the pivot points of said auxiliary struts at said auxiliary slider being equidistant from the axis of said shaft means and in a common plane perpendicular to the axis of said shaft means, and the pivot points of said auxiliary struts at said main struts being substantially equidistant from the pivot points where the main struts are secured to said outer rib members.
 3. A folding umbrella as defined in claim 1 wherein said crown is longitudinally shaped with opposite ends and elongated sides, said pivot points of each of said inner rib members being located about the perimeter of said longitudinally shaped crown whereby the pivot points of said inner rib members are at varying distances from the axis of shaft means.
 4. A folding umbrella as defined in claim 1 wherein said shaft means comprises a plurality of shaft members telescopically arranged whereby the length of said shaft means may be shortened or lengthened when said umbrella is folded or opened.
 5. A folding umbrella as defined in claim 3 wherein said rib assemblies are arranged in two groups pivotally secured to the flanks of said longitudinally shaped crown, said groups being spaced from each other on opposite sides of a plane passing through the axis of said shaft.
 6. A folding umbrella as defined in claim 5 wherein parallel walled slots are provided in the perimeter of said main slider for receiving and pivotally mounting the ends of the main struts, said slots being in two groups in axial alignment with the ends of said crown.
 7. A folding umbrella as defined in claim 13 wherein the pivot points of said inner rib members are arranged forming a rectangular configuration on said crown about the axis of said shaft means.
 8. A folding umbrella as defined in claim 2 wherein the main and auxiliary sliders comprise circular rims having slots for receiving the ends of the struts.
 9. A folding umbrella as defined in claim 2 wherein the pivot points for the struts secured to at least one of the sliders are irregularly spaced from each other.
 10. A folding umbrella as defined in claim 2 wherein slots are provided in the perimeters of said main and auxiliary sliders for receiving and pivotally mounting the ends of the struts, the slotS in the sliders in axial alignment with the ends of the crown having parallel walls and the slots in axial alignment with the elongated sides of the crown having wedge-shaped slots.
 11. A folding umbrella as defined in claim 10 wherein a pair of slots on opposite sides of the auxiliary slider are wedge-shaped and the remaining slots have parallel walls.
 12. A folding umbrella as defined in claim 10 wherein a pair of slots on opposite sides of the main slider are wedge-shaped and the remaining slots have parallel side walls.
 13. In a folding umbrella a. shaft means, b. a plurality of rib assemblies each comprising an inner rib member and an outer rib member slidably mounted on said inner rib member whereby the length of each rib assembly may be varied, said inner and outer rib members being of substantially equal lengths respectively, c. means for pivotally securing one end of each of said inner rib members about the axis of said shaft means, d. a main slider movable along said shaft means, and e. a plurality of struts of equal length, one end of each strut being pivotally secured to said main slider and the opposite end pivotally secured to said outer rib member, the pivot points where said struts are secured to said main slider being in a common plane perpendicular to the axis of said shaft means and the pivot points where said struts are secured to said outer rib members being substantially equidistant from the free ends of said outer rib members, the pivot points of said inner rib members forming a different configuration about the axis of said shaft means than the configuration formed about the axis of said shaft means by said pivot points of said struts at said mean slider, f. whereby when the umbrella is fully opened the perimeter of the umbrella defined by the free ends of the rib assemblies will assume a configuration substantially the same as the configuration of the pivot points of said struts at said main slider.
 14. A folding umbrella as defined in claim 13 wherein the pivot points of said rib assemblies are arranged forming a rectangular configuration about the axis of said shaft means and the pivot points of said struts are arranged forming a circular configuration about the axis of said shaft means.
 15. A telescopic umbrella comprising a. a shaft, b. a longitudinally extending crown located transversely on one end of said shaft, c. a main slider on said shaft, d. an auxiliary slider on said shaft between said crown and main slider, and e. a plurality of frame support units each comprising a rib assembly, a main strut, and an auxiliary strut, f. each of said rib assemblies comprising an inner rib member and an outer rib member which are telescopically slidably assembled, said inner and outer rib members being of substantially equal lengths respectively, g. said rib assemblies being arranged in two groups pivotally secured to the flanks of said longitudinally extending crown, said groups being spaced from each other on opposite sides of a plane passing through the axis of said shaft, and the pivot points of said inner rib members on said flanks being at varying distances from the axis of said shaft, h. the main and auxiliary sliders comprising rims having slots for pivotally securing one end of each of the main and auxiliary struts respectively, the pivot points where said main and auxiliary struts are secured to said main and auxiliary sliders respectively being arranged on substantially circular configuration, each circular configuration being in a common plane perpendicular to the axis of said shaft, i. the opposite end of each of said main struts being pivotally secured to said outer rib members, the pivot points where said main struts are secured to said outer rib members being substantially equidistant from the free ends of said outer rib members, j. the opposite end of each of said auxiliary struts being pivotally secured to a main strut, the pivot points of saId auxiliary struts at said main struts being substantially equidistant from the pivot points where the main struts are secured to said outer rib members, k. whereby when the umbrella is fully opened the perimeter of the umbrella defined by the ends of the rib assemblies will be substantially circular.
 16. An umbrella as claimed in claim 15 wherein the pivot points for the main and auxiliary struts are equally spaced around the periphery of the corresponding sliders.
 17. An umbrella as claimed in claim 15 wherein parallel walled slots are provided in the perimeter of said main slider for receiving and pivotally mounting the ends of the main struts, said slots being in two groups in axial alignment with the narrow sides of said crown.
 18. A telescopic umbrella frame comprising a. a shaft, b. a longitudinally shaped crown substantially at one end of said shaft, said crown having a pair of flanks on opposite sides of said shaft, respectively, c. a main slider and an auxiliary slider both movable along said shaft, and d. a plurality of support units, each unit comprising a rib assembly, a main strut, and an auxiliary strut, e. each said rib assembly comprising an inner rib member and an outer rib member slidably mounted on said inner rib member, whereby the length of each rib assembly may be varied, said inner rib members, outer rib members, main struts, and auxiliary struts being of substantially equal lengths respectively, f. one end of each said main strut being pivotally secured to said main slider, said pivot points about said main slider being substantially equidistant from the axis of said shaft and being in a common plane perpendicular to the axis of said shaft, and the opposite end of each of said main struts being pivotally secured to said outer rib member, said pivot points where said main struts are secured to said outer rib members being substantially equidistant from the free ends of said outer rib members, g. one end of each said auxiliary strut being pivotally secured to said auxiliary slider, said pivot points about said auxiliary slider being substantially equidistant from the axis of said shaft and being in a further common plane perpendicular to the axis of said shaft, and the opposite end of each of said auxiliary struts being pivotally secured to said main strut, said pivot points of said auxiliary struts at said main struts being substantially equidistant from the pivot points where the main struts are secured to said outer rib members, h. one end of each of said inner ribs of said rib assemblies being pivotally secured to the flanks of said crown, the pivot points of said inner rib members being at varying distances from the axis of said shaft, i. whereby the umbrella frame may be folded compactly and when opened the perimeter of the umbrella defined by the ends of the rib assemblies will be substantially circular. 